Independently and not as an agent of the Government, the Contractor shall exert its best efforts to perform as follows in the sequence shown: Isolate and characterize CEA-S from colon carcinomas (10-15 kilograms) to be supplied by the Government; Perform specific antisera to CEA-S; and Develop an optimally specific, sensitive, and standardized assay system for CEA-S. Approximately 100 normal and 180 disease serum/plasma for assay development will be provided by the Government. Evaluation of the assay for CEA-S shall be performed through use of coded sera from cancer patients in various stages of disease and from serially collected specimens of patients with known clinical history within the first year of the contract; the makeup of these panels shall be under the guidance of NCI staff.